Troldesh

Troldesh is ransomware — a malware that demands a payment in order to unlock encrypted files. It is also can search and steal information from the banking programs if such are found on the infected machine.

Type
Ransomware
Origin
Unknown
First seen
1 January, 2014
Last seen
10 July, 2020
Also known as
Encoder.858
Global rank
16
Week rank
27
Month rank
32
IOCs
644

What is Troldesh?

Troldesh, also know as Encoder.858 is ransomware belonging to the Shade ransomware family. It was created in 2014. The malware encrypts files on the victim’s machine and demands a ransom for the data to be restored.

Attempting to get as much information as possible the malware also scans the target PC for banking files or banking programs, in an effort to squeeze every last penny.

General description of Troldesh

Attacking Windows users mainly in Russia, Ukraine, and Germany, Troldesh is one of the three most commonly used encryption software in Russia.

In addition to this behavior, Troldesh ransomware often comes in conjunction with two particular malware samples, namely Mexar, and Teamspy, which allows attackers to control the victim's PC remotely and gives the virus the ability to install other malware on the infecting PC.

In fact, unlike most other ransomware, this virus does not stop executing after encrypting the victim’s files but instead starts an infinite loop where it requests URLs of other malicious programs from the command server, downloading and installing them on a contaminated machine. This means that most victims contaminated with Troldesh, in fact, may end up with a whole host of infections on their PC.

Even though the malware itself has not evolved a lot throughout its lifespan, the method which attackers use to demand the ransom has changed. The first malware samples used to provide an email address at which the victim could contact the hackers and negotiate the payment, whereas in newer campaigns ransom node demands victims to use the Tor browser in order to navigate to a payment page that is located on the Dark Web.

Being a part of the Shade family, Trodlesh shares several familiarities with related malware. As such, all members of the family are written in C++ and utilize CTL. Another shared feature is a static link with a Tor client. Every particular malware sample also has a hardcoded URL of the command server. Malicious programs of this family are also known to exhibit similar or identical behavior. As such, they create 10 identical ransom notes in two languages – Russian and English and name them README1.txt or README10.txt.

Troldesh malware analysis

A video simulation recorded on ANY.RUN allows us to examine the lifecycle of the Troldesh malware in a lot of detail.

process graph of a troldesh ransomware execution Figure 1: Process graph generated by ANY.RUN helps us visualize the life cycle of the virus

Troldesh execution process

Troldesh ransomware is spread in the form of a script file, either Javascript or JScript. Usually, these files are packed in an archive file, that is sometimes protected with a password. In the simulation performed on ANY.RUN, after a script file was unpacked and launched, it installed an executable file from the internet. It should be noted, that in the case of Troldesh, executable files normally have "not suspicious" extensions along the likes of .jpg. After being downloaded, the files are renamed and executed.

As shown in the ANY.RUN simulation, after running, the file immediately began performing malicious activity, namely: encrypting files, stealing personal data, deleting shadow copies and changing autorun values in the registry. Files encrypted by the latest versions of Troldesh are known to have .crypted000007 extension which was also the case in our simulation. Lastly, after encryption was completed the malicious executable file dropped ransomware instructions on the desktop.

process tree of a troldesh ransomware execution Figure 2: Process tree of a Troldesh ransomware execution

How to avoid infection by Troldesh?

Since Troldesh is commonly distributed using malspam campaigns that mimic real company newsletters, a good way of staying safe is thoroughly checking for the authenticity of emails before downloading any attachments. If necessary, one can get in touch with a company who is the presumable author of the newsletter and verify that they have, in fact, sent the email.

Once infected, Troldesh installs several secondary malware samples on the victim’s PC, thus after Troldesh itself is cleansed from the PC, it is important to conduct a global system scan and make sure that one’s machine is not swarming with other viruses as well.

Distribution of Troldesh

Troldesh ransomware is known to utilize two main attack vectors – email spam and exploit kits. Malspam campaigns usually mimic legitimate information newsletters from real Russian companies, including banks and large supermarket chains. The emails themselves contain an archive file in which another script file is included.

Upon unpacking the archive and clicking on the file, a malicious loader is installed. It in turn downloads and installs the main payload – Troldesh itself. The loader is known to be stored on legitimate but compromised Wordpress websites where it is hidden as an image file.

Troldesh is also known to utilize Axpergle and Nuclear exploit kits, and these attacks are, arguably, even more dangerous than email spam as they don’t require active actions from the user for contamination process to begin. Instead, upon visiting a compromised URL, which can be a website hosted by the attackers or a legitimate website that has been hacked, the malware utilizes a vulnerability either in the browser itself or in one of the browser plugins, successfully penetrating into the users PC and starting the execution automatically. Thus, victims can get infected without ever realizing the danger.

Communication with C&C

Address information of C&C servers is embedded in the body of each malware sample. Servers themselves are hosted on the dark web and communication is established with the use of a Tor client.

Once installed on a victim's PC, the malware requests a public key value from the server to encrypt the victim’s files. Should the connection attempt fail, the virus uses one of one hundred private key values stored in its memory.

How to detect Troldesh using ANY.RUN?

Since Troldesh ransomware writes into registry analysts can detect it by looking at registry keys. Choose the process by clicking on it in the process tree of the task then click on the "More info" button. In "Advanced details of process" window switch to the "Registry changes" tab and take a closer look. If the analyzed sample writes a value "906D0F2E2F604F839E04" with the name "xi" into the key HKLM\SOFTWARE\System32\Configuration it's Troldesh.

Registry changes created by Troldesh Figure 3: Registry changes created by Troldesh

Conclusion

Troldesh is an extremely dangerous ransomware that is able to contaminate victims who simply end up browsing to the wrong place at the wrong time, ending up on a website hacked by the attackers. Unlike much other ransomware that simply demands money in exchange for user’s encrypted data, Troldesh doesn’t stop there and goes the extra mile to spread other dangerous malware samples on a victim’s PC.

Utilizing analysis services like ANY.RUN is a great way to examine the virus from a safe environment and develop a sufficient defense strategy.

P.S.

On the 27th April, 2020 authors behind Troldesh ransomware announced that they stopped distribution of the ransomware and publish the decryption keys with decryption soft and instructions. They said that apologize to all the victims of the trojan and hope that the keys they published will help them to recover their data. You can take a look at the task in which their keys and tool were used to decrypt data.

IOCs

IP addresses
104.16.155.36
66.171.248.178
104.16.154.36
Hashes
a50f1be63ef1f51feac8f36a1b03664c4b6e8914633f6d71c5c7007984caf93c
2aab13d49b60001de3aa47fb8f7251a973faa7f3c53a3840cdf5fd0b26e9a09f
f5e37cb9087f7888f92b07d395427635d70c1c6c236287f5445957ce6765373b
0774ee18a57ee8a20d7f355f23a6b7f049dd93c251e2cc9af0100e92a3526547
c245d578954ad090885b600405dad467267db22c7dc1754f49ea6eb1b59dcad9
da2c1faca41b047192030d07b7647d202300d2215fc4fc08dd0a99bade42ef16
251e5b6f2b31c12ba7faf8e3f1a3b70d0988dcc66cfc9d52303c22a8077687b3
9ea254371b091687941c755963053907ef54ef77716d3a6d7d283bcd54351295
c06ccfc46f50f03bd0b7e8859fdd3432620feaf290eee1fd9daa933e2efb98ba
d54b643d3d92673bc08c5a4367159a52b410c2daf38616c84e3f9e1e28cb3bb3
943f55fdb67eaa648f0fd18f68ce89312dd8ad8a7a0a40a817bf35faa3a9d99f
9616eff1437e98fbe7360b61f3786d643b5c5eb4f57edb8b4d65884084676e18
14fe0fa7e16253e53ce4c25616e08006ad09330bea8df9161a47b2815cd83067
6556303d76c57a172c38ce49630acbceb6b5fb9f033a9ff0c3d1ad5668269c32
7ce52df2e1186532c119b3ad42fad1012bb78e6393bff209086dec386bbd49af
7ecc10ed2094d8eabfc4aa782bd681953dd12349385b030b582cc96cf2e74e41
e5ac3b675d297364b7b9f270f17caf264fe6ed7625baf8e54f4b94644a641174
b5fa77609effa05423d0ba2e9629a86ab57e05a7860fa711cb99ef61c6ce8525
94b88650ebf3fe56877d27316b51a4ddf27b4182892b167b5b03b35d84c95d02
5ca1242b2c692c6b4f65bc1e43d5ed3fab9f1b4a3bad69745a111d7a3a12f0a5
Domains
elx01.knas.systems
isns.net
majul.com
e8960.b.akamaiedge.net
qxq.ddns.net
www.whatismyipaddress.com
www.whatsmyip.net
www.planiligue.com
hunterdekaron.net
bb-sandonato.com

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